Everyone has their own opinions about what works and what doesn't. I think you've just opened a can of worms here......
We can't really answer your question without knowing what your goals are, what your diet is like, or whether you're a male or female. Fill out your profile and that would help out a lot. Thanks!
-------------- --JBennett "I've up-ed my intensity.... now up yours!" "Pain is only weakness leaving the body."
I think the key is taste. If it tastes lousy, I just won't use it. Twinlab products come to mind as the king of bad tasting protein drinks.
I like Nitro-Tech (with 20g per serving) and Designer Whey (with 17.5 g per serving). Both taste great when mixed with skim milk -- which adds even more protein.
Met-Rx products are also good, but a little expensive.
I've tried the mega protein shakes, and I truthfully don't see the need. They're usually more expensive per serving, and if you figure that most lifters need somewhere around a gram to a gram and a half of protein per pound of body weight per day, you can get that pretty quick with a balanced diet and a couple of shakes with a reasonable amount of protein.